Cohort Profile Update: The Swiss Eosinophilic Esophagitis Cohort Study (SEECS)

Introduction: The Swiss Eosinophilic Esophagitis Cohort Study (SEECS) is a national cohort that was established in 2015 with the aim of improving quality of care of affected adults with eosinophilic esophagitis (EoE). Between 2020 and 2022, paper questionnaires were gradually replaced by fully electronic data capture using Research Electronic Data Capture (REDCap®) software. We aim to provide an update of the SEECS eight years after its launch. Methods: The SEECS prospectively includes adults (≥18 years of age) with EoE as well as patients with gastro-esophageal reflux disease (GERD) and healthy control subjects (HC). Upon inclusion and follow-up (typically once every 12-18 months), patients and physicians complete REDCap® questionnaires, which are available in German, French, and English. Patient-reported outcomes (PROs) and biologic findings are assessed on the same day using validated instruments (EEsAI PRO for symptoms; EoE-QoL-A for QoL; EREFS for endoscopic activity; modified EoE-HSS for histologic activity). The SEECS biobank includes biosamples from patients with EoE, GERD, and HC. Results: As of July 2023, the SEECS included 778 patients [716 (92%) with EoE, 29 (3.8%) with GERD, and 33 (4.2%) HC; 559/778 (71.9%) were male]. Mean age±SD (years) at enrollment according to diagnosis was as follows: EoE 41.9±12.9, GERD 53.6±16.4, HC 51.7±17.2. Concomitant GERD was found in 200 patients (27.9%) of the EoE cohort. Concomitant allergic disorders (asthma, rhinoconjunctivitis, eczema) were present in 500 EoE patients (74.4%). At inclusion, 686 (95.8%) of EoE patients were on ongoing treatment [orodispersible budesonide tablet (Jorveza®) in 281 patients (41%); budesonide or fluticasone syrup or swallowed powder in 290 patients (42.3%); proton pump inhibitors in 162 patients (23.6%); elimination diets in 103 patients (15%); and esophageal dilation at last visit in 166 patients (24.2%)]. A total of 8,698 biosamples were collected, of which 1,395 (16%) were used in the framework of translational research projects. Discussion: SEECS continuously grows and is operational using fully electronic data capture. SEECS offers up-to-date epidemiologic and real-world clinical efficacy data on EoE and promotes clinical and translational research.